| 1. |
- Chambi, Diego, et al.
(författare)
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Exopolysaccharides production by cultivating a bacterial isolate from the hypersaline environment of salar de uyuni (Bolivia) in pretreatment liquids of steam-exploded quinoa stalks and enzymatic hydrolysates of Curupaú sawdust
- 2021
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Ingår i: Fermentation. - : MDPI. - 2311-5637. ; 7:1
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Tidskriftsartikel (refereegranskat)abstract
- The halotolerant bacterial strain BU-4, isolated from a hypersaline environment, was identified as an exopolysaccharide (EPS) producer. Pretreatment liquids of steam-exploded quinoa stalks and enzymatic hydrolysates of Curupaú sawdust were evaluated as carbon sources for EPS production with the BU-4 strain, and the produced EPS was characterized using FTIR, TGA, and SEM. Cultivation was performed at 30◦C for 48 h, and the cells were separated from the culture broth by centrifugation. EPS was isolated from the cell pellets by ethanol precipitation, and purified by trichloroacetic acid treatment, followed by centrifugation, dialysis, and freeze-drying. EPS production from quinoa stalks-and Curupaú sawdust-based substrates was 2.73 and 0.89 g L−1, respectively, while 2.34 g L−1 was produced when cultivation was performed on glucose. FTIR analysis of the EPS revealed signals typical for polysaccharides, as well as ester carbonyl groups and sulfate groups. High thermal stability, water retention capacity and gel-forming ability were inferred from SEM and TGA. The capability of the halotolerant isolate for producing EPS from pretreatment liquids and hydrolysates was demonstrated, and characterization of the EPS revealed their broad application potential. The study shows a way for producing value-added products from waste materials using a bacterium from a unique Bolivian ecosystem.
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| 2. |
- Daga-Quisbert, Jeanett, et al.
(författare)
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Analysis of the microbiome of the Bolivian high-altitude Lake Pastos Grandes
- 2023
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Ingår i: FEMS Microbiology Ecology. - : Oxford University Press (OUP). - 0168-6496 .- 1574-6941. ; 99:8
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Tidskriftsartikel (refereegranskat)abstract
- Lake Pastos Grandes in Bolivia is mainly composed of salt flats, which are sporadically and only partially submerged during the wet season. In the present study, the chemical composition of water samples of the lake and some influent rivers was determined. We found that it is likely that the lake was influenced by the dilution of metals from ancient evaporites. We performed the first metagenomic studies of this lake. Analyses of shotgun metagenomics revealed that the relative abundances of Burkholderiales and Pseudomonadales were noteworthy in the water samples, whereas the archaea belonging to the Halobacteriales and Cyanobacteria from subsection III had high abundances in the salt flat. The eukaryotes Crustacea and Diatomea exhibited the highest abundances in the water samples. We investigated further the potential effect of human activities on the nitrogen cycle mobilization in the lake and the propagation of antimicrobial resistance genes. This is the first report about the cycle in the lake. Additionally, rifamycin resistance genes and genes related to efflux pumps, which are not considered a hazard when identified in metagenomes, had the uppermost relative abundances in all sampling points. We found that Lake Pastos Grandes hitherto does not show an appreciable influence by anthropogenic actions. The microbiome of Lake Pastos Grandes, including microbial distribution, the nitrogen cycle and antibiotic resistance genes, was analyzed.
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| 3. |
- Daga-Quisbert, Jeanett, et al.
(författare)
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Assessing water quality of a hypereutrophic alkaline urban lake and its coagulation-treated water using metagenomic analysis
- 2024
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Ingår i: Water, Air and Soil Pollution. - : Springer Nature. - 0049-6979 .- 1573-2932. ; 235:6
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Tidskriftsartikel (refereegranskat)abstract
- The study on Lake Alalay, an urban alkaline lake facing increasing pollution, focused on the impact of coagulation treatment on its water quality and microbiome. The findings revealed higher nutrient concentrations, specifically phosphate and ammonium, compared to the 2019 benchmark. The lake was found to be dominated by Proteobacteria, followed by Cyanobacteria, with Desulfobacterota thriving in areas with low dissolved oxygen. Arthrospira and Roseobacter, halo-alkali-tolerant photosynthetic bacterial genera, were detected at all sampling points. Local phosphate and oxygen concentration variations led to distinct microbial communities on the lake's surface. Despite these differences, long-term ex-situ studies on water treatment with iron chloride and poly-aluminum chloride reduced the relative abundance of Cyanobacteria, promoting the presence of Proteobacteria and Bacteroidota. However, the coagulants required higher quantities than those typically used in small shallow lakes to precipitate phosphate and improve water quality effectively. Furthermore, the large-scale assay of lake water treatment with coagulants failed to eliminate Vibrio and Acinetobacter multidrug-resistant bacteria. In conclusion, the study underscores the need to prevent the inflow of polluted water into Lake Alalay and implement effective measures to deal with the existing chemical and biological contamination.
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| 4. |
- Delgado, Osvaldo, et al.
(författare)
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Nesterenkonia aethiopica sp nov., an alkaliphilic, moderate halophile isolated from an Ethiopian soda lake
- 2006
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Ingår i: International Journal of Systematic and Evolutionary Microbiology. - : Microbiology Society. - 1466-5026 .- 1466-5034. ; 56:6, s. 1229-1232
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Tidskriftsartikel (refereegranskat)abstract
- T Strain DSM 17733(T), isolated from the shore of Lake Abjata in Ethiopia, is a heterotrophic, alkaliphilic, moderately halophilic, Gram-positive, strictly aerobic, non-motile, non-endospore-forming bacterium. The organism grows optimally at 30-37 degrees C, pH 9 and 3 % (w/v) NaCl. Analysis of the cell wall showed the presence of murein of the type L-Lys-Gly-L-Glu, variation A4 alpha. The G + C content of the genomic DNA was 69(.)0 mol%. Sequence analysis of 16S rRNA gene sequence of strain DSM 17733(T) placed the isolate in the genus Nesterenkonia. DNA-DNA hybridization of DSM 17733(T) with those organisms with the closest phylogenetic affiliation, i.e. Nesterenkonia halobia, Nesterenkonia facusekhoensis and Nesterenkonia xinjiangensis, gave relatedness values of 48.5 %, 63(.)7 % (repetition, 57(.)2 %) and 35(.)7 % (repetition, 29(.)3 %), respectively. On the basis of both phenotypic and phylogenetic criteria and the low levels of DNA-DNA relatedness with the phylogenetically closest species N. xinjiangensis and N. halobia, it is proposed that the isolate be classified in a novel species, Nesterenkonia aethiopica sp. nov. The type strain is DSM 17733(T) (=CCUG 48939(T)).
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| 5. |
- Doan Van, Thuoc, et al.
(författare)
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High productivity of ectoines by Halomonas boliviensis using a combined two-step fed-batch culture and milking process.
- 2010
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Ingår i: Journal of Biotechnology. - : Elsevier BV. - 1873-4863 .- 0168-1656. ; 147:1, s. 46-51
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Tidskriftsartikel (refereegranskat)abstract
- A process comprising two-step fed-batch cultivation has been investigated for the production of ectoines using the halophilic bacterium Halomonas boliviensis DSM 15516(T). The first cultivation was performed under optimal conditions for cell growth and resulted in cell mass concentration of about 41gl(-1) after 24h of cultivation. During the second cultivation at higher salt concentration, accumulation of ectoines increased while cell mass decreased with increasing salt concentration. Maximum productivity of total ectoines reached was 10gl(-1)d(-1) with ectoine concentration of 6gl(-1) and hydroxyectoine concentration of 8gl(-1) after 9h of cultivation at 18.5% NaCl, which is among the highest reported so far. H. boliviensis cells were further recycled for the production process after releasing the ectoines. About 75% of the accumulated ectoines were released by subjecting the cells to hypoosmotic shock. On subsequent reincubation in a medium containing higher salt concentration the cells were able to re-synthesize the ectoines resulting in a global productivity of 11.1gl(-1)d(-1), and ectoine and hydroxyectoine productivities of 9.1gl(-1)d(-1) and 2.0gl(-1)d(-1), respectively.
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| 6. |
- Doan Van, Thuoc, et al.
(författare)
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Utilization of agricultural residues for poly(3-hydroxybutyrate) production by Halomonas boliviensis LC1
- 2008
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Ingår i: Journal of Applied Microbiology. - : Oxford University Press (OUP). - 1364-5072 .- 1365-2672. ; 104:2, s. 420-428
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Tidskriftsartikel (refereegranskat)abstract
- Aims: Utilization of cheap and readily available agricultural residues as cheap carbon sources for poly(3-hydroxybutyrate) (PHB) production by Halomonas boliviensis. Methods and results: Wheat bran was hydrolysed by a crude enzyme preparation from Aspergillus oryzae NM1 to provide a mixture of reducing sugars composed mainly of glucose, mannose, xylose and arabinose. Growth of H. boliviensis using a mixture of glucose (0.75% w/v) and xylose (0.25% w/v) in the medium led to a PHB content and concentration of 45 wt% and 1 g l(-1), respectively, after 30 h. A similar PHB concentration was attained when H. boliviensis was grown on wheat bran hydrolysate but with a lower PHB content, 34 wt%. In a batch cultivation mode in a fermentor, using 1.8% (w/v) reducing sugars, the maximum PHB accumulation by H. boliviensis was attained in 20 h, but was reduced to about 30 wt%. By adding butyric acid (0.8% v/v), sodium acetate (0.8% w/v) and decreasing the reducing sugars concentration to 1.0% w/v in the medium, PHB accumulation and concentration were increased to 50 wt% and 4 g l(-1), respectively, after 20 h. Butyric acid and sodium acetate for PHB production could also be provided by anaerobic digestion of solid potato waste. Conclusions: Cheap and readily available agricultural residues can be used as substrates to produce PHB. The production of PHB by H. boliviensis using wheat bran hydrolysate as source of carbon is expected to reduce the production cost and motivates further studies. Significance and Impact of the Study: Large-scale commercial utilization of PHB is mainly hampered by its high production cost. Carbon source for PHB production accounts up to 50% of the total production costs. Thus, the use of waste agricultural residues can substantially reduce the substrate cost (and in turn even provide value to the waste), and can downsize the production costs. This improves the market competitiveness. Studies on PHB production by moderate halophiles were recently initiated with H. boliviensis and findings show that it has potential for commercial exploitation. PHB production by H. boliviensis using wheat bran and potato waste is hence interesting.
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| 7. |
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| 8. |
- Guevara-Martínez, Mónica, 1989-, et al.
(författare)
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Regulating the production of (R)-3-hydroxybutyrate in Escherichia coli by N or P limitation
- 2015
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Ingår i: Frontiers in Microbiology. - : Frontiers Research Foundation. - 1664-302X. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- The chiral compound (R)-3-hydroxybutyrate (3HB) is naturally produced by many wild type organisms as the monomer for polyhydroxybutyrate (PHB). Both compounds are commercially valuable and co-polymeric polyhydroxyalkanoates have been used e.g., in medical applications for skin grafting and as components in pharmaceuticals. In this paper we investigate cultivation strategies for production of 3HB in the previously described E. coil strain AF1000 pJBGT3RX. This strain produces extracellular 3HB by expression of two genes from the PHB pathway of Halomonas boliviensis. H. boliviensis is a newly isolated halophile that forms PHB as a storage compound during carbon excess and simultaneous limitation of another nutrient like nitrogen and phosphorous. We hypothesize that a similar approach can be used to control the flux from acetylCoA to 3HB also in E coli; decreasing the flux to biomass and favoring the pathway to the product. We employed ammonium- or phosphate-limited fed-batch processes for comparison of the productivity at different nutrient limitation or starvation conditions. The feed rate was shown to affect the rate of glucose consumption, respiration, 3HB, and acetic acid production, although the proportions between them were more difficult to affect. The highest 3HB volumetric productivity, 1.5 g L-1 h(-1), was seen for phosphate-limitation.
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| 9. |
- Guevara-Martínez, Mónica, 1989-, et al.
(författare)
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The role of the acyl-CoA thioesterase YciA in the production of (R)-3-hydroxybutyrate by recombinant Escherichia coli
- 2019
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Ingår i: Applied Microbiology and Biotechnology. - : Springer. - 0175-7598 .- 1432-0614. ; , s. 1-12
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Tidskriftsartikel (refereegranskat)abstract
- Biotechnologically produced (R)-3-hydroxybutyrate is an interesting pre-cursor for antibiotics, vitamins, and other molecules benefitting from enantioselective production. An often-employed pathway for (R)-3-hydroxybutyrate production in recombinant E. coli consists of three-steps: (1) condensation of two acetyl-CoA molecules to acetoacetyl-CoA, (2) reduction of acetoacetyl-CoA to (R)-3-hydroxybutyrate-CoA, and (3) hydrolysis of (R)-3-hydroxybutyrate-CoA to (R)-3-hydroxybutyrate by thioesterase. Whereas for the first two steps, many proven heterologous candidate genes exist, the role of either endogenous or heterologous thioesterases is less defined. This study investigates the contribution of four native thioesterases (TesA, TesB, YciA, and FadM) to (R)-3-hydroxybutyrate production by engineered E. coli AF1000 containing a thiolase and reductase from Halomonas boliviensis. Deletion of yciA decreased the (R)-3-hydroxybutyrate yield by 43%, whereas deletion of tesB and fadM resulted in only minor decreases. Overexpression of yciA resulted in doubling of (R)-3-hydroxybutyrate titer, productivity, and yield in batch cultures. Together with overexpression of glucose-6-phosphate dehydrogenase, this resulted in a 2.7-fold increase in the final (R)-3-hydroxybutyrate concentration in batch cultivations and in a final (R)-3-hydroxybutyrate titer of 14.3 g L-1 in fed-batch cultures. The positive impact of yciA overexpression in this study, which is opposite to previous results where thioesterase was preceded by enzymes originating from different hosts or where (S)-3-hydroxybutyryl-CoA was the substrate, shows the importance of evaluating thioesterases within a specific pathway and in strains and cultivation conditions able to achieve significant product titers. While directly relevant for (R)-3-hydroxybutyrate production, these findings also contribute to pathway improvement or decreased by-product formation for other acyl-CoA-derived products.
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| 10. |
- Guzmán, Daniel, et al.
(författare)
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Halomonas andesensis sp. nov., a moderate halophile isolated from the saline lake Laguna Colorada in Bolivia.
- 2010
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Ingår i: International Journal of Systematic and Evolutionary Microbiology. - : Microbiology Society. - 1466-5026 .- 1466-5034. ; 60, s. 749-753
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Tidskriftsartikel (refereegranskat)abstract
- Strain LC6T was isolated from a water sample of the lake Laguna Colorada in the Bolivian Andes. The bacterium was characterized as moderately halophilic, motile, Gram-negative rod. The major fatty acids present in the cell were C18:1omega7c, C16:1omega7c iso 2-OH, C16:0 and C12:0 3-OH. The respiratory ubiquinones found in strain LC6T were Q-9 (97%) and Q-8 (3%). The organism was found to be an aerobic, heterotroph, able to utilize various carbohydrates and other substrates as carbon source. The G+C content (mol %) of the genomic DNA was 52.5. The organism was able to grow in the pH range of 6.0-11.0 (optimum between 7.0-8.0), temperature of 4-45 degrees C (optimum at 30-35 degrees C) and sodium chloride concentration of 0.5-20 % (w/v) (optimum between 1-3% w/v). Based on 16S rRNA gene sequence analysis, LC6T was 98.8 % similar to Halomonas hydrothermalis DSM 15725T and Halomonas venusta DSM 4743T, and 98.4 % similar to Halomonas aquamarina DSM 30161T, Halomonas axialensis DSM 15723T and Halomonas meridiana DSM 5425T. However, its DNA-DNA relatedness with these type strains was considerably low. LC6T resembled other Halomonas species with respect to various physiological, biochemical, and nutritional characteristics. Combined phenotypic data and DNA-DNA hybridization data supported the conclusion that LC6T is a novel species of the genus Halomonas, for which the name Halomonas andesensis (LC6T=CCUG 54844T=LMG 24243T = DSM 19434T) is proposed.
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